1. Field of the Invention
The invention relates to a vehicle control system that is configured to control behavior characteristics or acceleration/deceleration characteristics (which will be called “running characteristics”) of the vehicle, such as a power characteristic, a steering characteristic and a suspension characteristic of the vehicle, so that the running characteristics match a running environment and driver's preferences and intention regarding running.
2. Description of the Related Art
While the vehicle behavior, such as a vehicle speed and a running direction, varies according to the driver's accelerating/decelerating operation and steering operation, the relationship between the amount of the driver's operation and the amount of change of the behavior is determined not only by the energy efficiency, such as a fuel efficiency, but also by characteristics, such as a ride comfort, quietness and power performance, which are required of the vehicle.
In the meantime, environments in which the vehicle runs include a wide variety of surroundings or road types, such as an urban area, an expressway, a winding road, an uphill, and a downhill, and there are a variety of driver's preferences and intentions regarding running, and there are a variety of impressions the driver receives from the vehicle during running. Therefore, an expected running characteristic is not necessarily obtained if the running environment changes or the vehicle is driven by another driver. As a result, so-called driveability may deteriorate.
Thus, one type of vehicle has been developed which is arranged to manually select running characteristics, such as a power output characteristic (or acceleration characteristic) and a suspension characteristic, concerning the behavior of the vehicle, by operating a mode selection switch. Namely, the vehicle is arranged to select a drive mode from, for example, a sporty mode in which the vehicle runs with an excellent accelerating ability, and the suspension is set to be somewhat hard, a normal mode in which the vehicle accelerates at a relatively low rate, and has a relatively soft suspension characteristic, and an eco mode in which the fuel economy or efficiency is prioritized by operating the switch.
Also, various systems have been proposed which are configured to cause the driving orientation to be reflected by behavior control of the vehicle. This type of system does not necessitate any switching operation, and permits changes of subtle or detailed characteristics. One example of this type of system is described in Japanese Patent Application Publication No. 06-249007 (JP-A-06-249007). In the system described in JP-A-06-249007, which is a driving force control system using a neurocomputer, the relationship of the acceleration with respect to the acceleration stroke and the vehicle speed is learned as a required acceleration model, and the throttle opening is calculated based on a deviation between the model and a second reference acceleration model that reflects the driver's orientation or preferences in connection with running, and a deviation between the second reference acceleration model and a first reference acceleration model as a standard model.
Also, a system that is configured to detect the driving characteristics or driving orientation while distinguishing those of the longitudinal direction of the vehicle from those of the lateral direction is described in Japanese Patent Application Publication No. 11-129924 (JP-A-11-129924). Further, Japanese Patent Application Publication No. 11-2320 (JP-A-11-2320) describes a system that is configured to engage a lock-up clutch, and prohibit shifting when it is detected that a vehicle is in a turning condition.
According to each of systems described in JP-A-06-249007, JP-A-2004-257434 and JP-A-11-2320, improvement needs to, be made to cause the request or driving orientation of the driver to be accurately reflected by the running characteristics.